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An investigation into the effect of surface area on the enzyme catalase.

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Introduction

An investigation into the effect of surface area on the enzyme catalase. Catalase By Andy Mc Namee The effect of surface area on the activity of catalase in potatoes Planning: *Hypothesis* hydrogen peroxide will breakdown to oxygen and water in the presence of Catalase. The reaction will increase with increasing enzyme concentration when molecules of hydrogen peroxide are freely available. However, when molecules of the substrate are in short supply, the increase in rate of reaction is limited and will have little effect. Enzymes are globular protein biological catalysts; it is called a catalyst because it helps speed up chemical reactions. As enzymes are globular, this means that they are coiled up into a 3-dimensional shape they have hydrophilic side chains on the outside to ensure that they are soluble. If they weren't soluble then they wouldn't be able to combine with substrates and help break them down. Enzymes also contain a depression or a cleft inside them, this is called the active site. This is where substrates are broken down for example the enzyme catalase has an active site so it will break down hydrogen peroxide into water and oxygen. The active site can also join two substrates together, for example a dipeptide. The active site isn't just a random hole, it has a specific size and shape, because of this precise cleft, the enzyme will only break down certain substrates, normally only one. Take for example; hydrogen peroxide into water and oxygen, this breakdown is caused by the enzyme catalase holding the hydrogen peroxide molecule in place and then breaks down the substrate whilst it is being held into place, by bonds between the side chains and the substrate. As the enzyme is only holding the substrate into place it isn't affected greatly and can carry this process out many times. Due to this much organised method of breaking down substrates, it can also be carried out very quickly. ...read more.

Middle

I had to find a way of collecting the amount of oxygen produced, this was very hard to measure, but I found that measuring how much water could be displaced was a better method because it wouldn't involve any machines and wouldn't become complicated. If any mistakes were made, then it would be through human error. By creating many tables of results, I would be able to find out which results were right, and which ones weren't. To follow this method, it involved oxygen to be collected in a measuring cylinder filled with water to see how much water was displaced. I used the Size 6 gorger and kept this constant all the way through my experiment otherwise the number of active sites available would be different allowing different amounts of oxygen and water to be collected. I used the highest molar solution, 2.0, because it means that most of the active sites on the potato would be taken up and wouldn't be inactive because there wasn't enough substrate to be broken down. When all the substrate has been broken down, the amount of oxygen and water produced, should plateau, this is why I am expecting my results to be closer together towards the end of the experiment. I created the experiment in the following way... Method 1) To start the experiment, take the size 6 potato gorger and gouge a few pieces of potato. 2) Take the gouged pieces of potato and cut them, by using the ruler and a razor blade, into lengths of 2 cm's, but make sure the end of the potato isn't used and is discarded. This is because the skin of the potato may have different properties to the actual inner pieces of the potato and would change the results from the experiment. 3) By using a ruler cut one of the potato pieces 20mm from one of the ends. ...read more.

Conclusion

There were bound to be a few seconds difference. Although I think the experiment isn't a very accurate one in terms of the number of variables affecting the results, I feel that the errors were small and couldn't have made a major difference to the overall readings. Any of the errors which I mentioned above all occurred to each test. If all the tests were affected in the same way, then the results couldn't have changed much. Whilst looking at my graphs, I noticed a couple of anomalies, they have been indicated on my graphs. I believe that these anomalies were caused by some of the errors which I mentioned above, although they wouldn't have made a major difference on their own, I feel that some of the errors would have happened to some test and maybe no errors happened to the others. This could also work both ways, maybe all the errors above happened to these anomalies, each error may have not affected the test much, but when all the errors occur then the total error could be massive and this is probably what happened with my anomalies. I think the best way to improve this experiment is to use a gas syringe instead of using the inverted measuring cylinder syringe. By using a gas syringe, it means that there won't need to be any water involved as the whole experiment is enclosed. This will reduce the amount of variables in the experiment, making it a lot more accurate. The gas syringe will be pushed up from the extra pressure from the releasing oxygen. Making it an easier way to capture the correct amount of oxygen. I conclude, from my experiment, that my hypothesis is correct and as surface area increases, so does the rate of reaction between catalase and hydrogen peroxide. By Andrew Mc Namee This document was downloaded from Coursework.Info - The UK's Coursework Database ?? ?? ?? ?? - 1 - ...read more.

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